From Oregon State University some news the team and especially Kevin Trenberth just really don’t want to hear. I covered this on a tip from Dr. Pat Michaels back on Nov 9th titled: Climate sensitivity- lowering the IPCC “fat tail” and now the official press release makes the publication well known. Their estimate is 2.4C for a doubling of CO2, which is still higher than Spencer and others have estimated but significantly lower than IPCC’s projections. A link to the paper follows below.
Climate sensitivity to CO2 more limited than extreme projections
CORVALLIS, Ore. – A new study suggests that the rate of global warming from doubling of atmospheric carbon dioxide may be less than the most dire estimates of some previous studies – and, in fact, may be less severe than projected by the Intergovernmental Panel on Climate Change report in 2007.
Authors of the study, which was funded by the National Science Foundation and published online this week in the journal Science, say that global warming is real and that increases in atmospheric CO2 will have multiple serious impacts.
However, the most Draconian projections of temperature increases from the doubling of CO2 are unlikely.
“Many previous climate sensitivity studies have looked at the past only from 1850 through today, and not fully integrated paleoclimate date, especially on a global scale,” said Andreas Schmittner, an Oregon State University researcher and lead author on the Science article. “When you reconstruct sea and land surface temperatures from the peak of the last Ice Age 21,000 years ago – which is referred to as the Last Glacial Maximum – and compare it with climate model simulations of that period, you get a much different picture.
“If these paleoclimatic constraints apply to the future, as predicted by our model, the results imply less probability of extreme climatic change than previously thought,” Schmittner added.
Scientists have struggled for years trying to quantify “climate sensitivity” – which is how the Earth will respond to projected increases of atmospheric carbon dioxide. The 2007 IPCC report estimated that the air near the surface of the Earth would warm on average by 2 to 4.5 degrees (Celsius) with a doubling of atmospheric CO2 from pre-industrial standards. The mean, or “expected value” increase in the IPCC estimates was 3.0 degrees; most climate model studies use the doubling of CO2 as a basic index.
Some previous studies have claimed the impacts could be much more severe – as much as 10 degrees or higher with a doubling of CO2 – although these projections come with an acknowledged low probability. Studies based on data going back only to 1850 are affected by large uncertainties in the effects of dust and other small particles in the air that reflect sunlight and can influence clouds, known as “aerosol forcing,” or by the absorption of heat by the oceans, the researchers say.
To lower the degree of uncertainty, Schmittner and his colleagues used a climate model with more data and found that there are constraints that preclude very high levels of climate sensitivity.
The researchers compiled land and ocean surface temperature reconstructions from the Last Glacial Maximum and created a global map of those temperatures. During this time, atmospheric CO2 was about a third less than before the Industrial Revolution, and levels of methane and nitrous oxide were much lower. Because much of the northern latitudes were covered in ice and snow, sea levels were lower, the climate was drier (less precipitation), and there was more dust in the air.
All these factor, which contributed to cooling the Earth’s surface, were included in their climate model simulations.
The new data changed the assessment of climate models in many ways, said Schmittner, an associate professor in OSU’s College of Earth, Ocean, and Atmospheric Sciences. The researchers’ reconstruction of temperatures has greater spatial coverage and showed less cooling during the Ice Age than most previous studies.
High sensitivity climate models – more than 6 degrees – suggest that the low levels of atmospheric CO2 during the Last Glacial Maximum would result in a “runaway effect” that would have left the Earth completely ice-covered.
“Clearly, that didn’t happen,” Schmittner said. “Though the Earth then was covered by much more ice and snow than it is today, the ice sheets didn’t extend beyond latitudes of about 40 degrees, and the tropics and subtropics were largely ice-free – except at high altitudes. These high-sensitivity models overestimate cooling.”
On the other hand, models with low climate sensitivity – less than 1.3 degrees – underestimate the cooling almost everywhere at the Last Glacial Maximum, the researchers say. The closest match, with a much lower degree of uncertainty than most other studies, suggests climate sensitivity is about 2.4 degrees.
However, uncertainty levels may be underestimated because the model simulations did not take into account uncertainties arising from how cloud changes reflect sunlight, Schmittner said.
Reconstructing sea and land surface temperatures from 21,000 years ago is a complex task involving the examination of ices cores, bore holes, fossils of marine and terrestrial organisms, seafloor sediments and other factors. Sediment cores, for example, contain different biological assemblages found in different temperature regimes and can be used to infer past temperatures based on analogs in modern ocean conditions.
“When we first looked at the paleoclimatic data, I was struck by the small cooling of the ocean,” Schmittner said. “On average, the ocean was only about two degrees (Celsius) cooler than it is today, yet the planet was completely different – huge ice sheets over North America and northern Europe, more sea ice and snow, different vegetation, lower sea levels and more dust in the air.
“It shows that even very small changes in the ocean’s surface temperature can have an enormous impact elsewhere, particularly over land areas at mid- to high-latitudes,” he added.
Schmittner said continued unabated fossil fuel use could lead to similar warming of the sea surface as reconstruction shows happened between the Last Glacial Maximum and today.
“Hence, drastic changes over land can be expected,” he said. “However, our study implies that we still have time to prevent that from happening, if we make a concerted effort to change course soon.”
Other authors on the study include Peter Clark and Alan Mix of OSU; Nathan Urban, Princeton University; Jeremy Shakun, Harvard University; Natalie Mahowald, Cornell University; Patrick Bartlein, University of Oregon; and Antoni Rosell-Mele, University of Barcelona.
===========================
Here’s the paper:
http://www.princeton.edu/~nurban/pubs/lgm-cs-uvic.pdf
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Your title is misleading. The authors of this study are extremely concerned about the effects of warming especially over land.They do warn that there is still time to prevent this from happening “if we make a concerted effort to change course soon”. WE have a clear choice: do nothing and await our fate; or act prudently, and optimize our chances of minimizing expected impacts.
REPLY: The title is fine, compared to IPCC and other even larger sensitivity estimates, which are in fact overestimated, this one at 2.4 C is lower. The Earth has had many events where if climate sensitivity to CO2 and other GHG’s were high, the event would have put Earth into a runaway warming path.
That’s never happened.
Earth’s climate sensitivity thus cannot be as high as some predict. And the only reason for that “concern” is to get past the gatekeeping that we have witnessed goes on in journals thanks to Climatgate showing the issue in sunlight.
Request denied. – Anthony
If they are applying the standard IPCC models to paleo climate then they are only looking at CO2 and volcanic aerosols as climate drivers. They still aren’t accounting indirect solar effects, which are strongly evidenced by high paleo-correlations between temp and cosmogenic isotopes (whether the mechanism is GCR-cloud or not). So it’s still the same old garbage.
ferd berple says:
Why? Because Nature emits 30 times as much CO2 each year as humans. By cutting down trees and NOT REPLACING them, as is happening in large areas of the third world to support population increases, humans are affecting natural CO2 levels.
Henry@ferd
I’m not sure what is your point.
Does it make a difference if you use trees, coal or oil for survival?
No,
except that if you cut trees it is going to get colder, as evident from my investigations.
What do want? if you live in a warm area, you might like it getting colder. Or if you live in a colder area, put up more trees.
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
http://www.letterdash.com/HenryP/more-carbon-dioxide-is-ok-ok
It’s a model-based result. If you don’t believe the models to be accurate, then there is no reason for you to believe this result. In fact, if you read the article in its entirety, they make a good case that the model is not accurate enough for its intended purpose. The authors are forthright and clear in addressing the limits of the knowledge encoded in the programs.
Septic says:
“If you don’t believe the models to be accurate, then there is no reason for you to believe this result.”
There are other reasons showing that the sensitivity number is highly exaggerated. One example out of many. I can post lots more if you like. Just ask.
Henry@Hugh Pepper
So what do you say about this?
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
This is some seriously flawed stuff. There is no reason to presume that sensitivity is linear and every reason to believe it isn’t. There are two great attractors in the climate system – all ice and no ice. These stable points are albedo driven. Ice begets ice and water begets water. For the past several million years the earth has been perched on a tipping point between the two great attractors. Sensitivity is high to EVERYTHING at the present time but once the ice is well established or well removed there’s little sensitivity left and one or the other of the stable states persist. The winner for over 90% of the earth’s history is no ice. Ice ages are periods of low activity for the biosphere. If anyone is truly interested in a green planet they certainly cannot be against a warmer planet, much warmer that it is today.
Hugh Pepper says:
November 25, 2011 at 8:38 am
[ ” WE have a clear choice: do nothing and await our fate; or act prudently, and optimize our chances of minimizing expected impacts.” ]
xxxxxxxxxxxxxxxxx
Ahhh………… Master Pascal’s Wager )
http://en.wikipedia.org/wiki/Pascal's_Wager
You are confusing a philosophical debate – with a [ supposed ] “scientific” debate.
@Anthony
Climate sensitivity to CO2 is quite unlikely to be linear. When the earth is at a tipping point between being dominated by ice or dominated by liquid water then the climate will be more sensitive than usual to ANYTHING that causes additional warming or cooling. There are two great attractors, all ice and no ice. Historically the latter is the more persistent. And you are certainly correct that there has never been a runaway greenhouse. That is limited by the third phase of H20, water vapor. As it gets warmer and warmer and more and more of the surface is covered by liquid there’s more evaporation and more clouds both of which cool the surface by first transporting heat away from the surface in latent heat of vaporization and second by forming highly reflective clouds which block warming sunlight from reaching the surface. On a water world like ours it’s the phases of water which run the show not the non-condensing composition of the atmosphere.
Henry@Dave Springer
Hi Dave, it is great that we find each other here.
The last time you said: Co2 has very little effect over the oceans which is 71% of the planet’s surface because the oceans only gives up 20% of its solar heating.
I am disputing that. I think you got it wrong.
For latest tables see:
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
I am now busy with a weatherstation in China, in Changsha and I am willing to place a bet with you that I will find some cooling there. And I think you know why we will find cooling there.
Steve Keohane says:
November 25, 2011 at 6:30 am
“Stephen, one additional factor, perhaps included in your own latitudinal shifts would be the restriction or movement of ocean currents to the equatorial zones only. In addition, the ocean surface would be reduced, I’m guessing , 25%ish. This surface area reduction would not only be the glacial extent from the poles, but would include increased land area from sea level reduction”
Yes I think there would likely be lots of second order effects apart from permanent climate zone shifting and you mention a couple of possibilities.
Further examples are those suggested by other contributors here such as HenryP, Vuk, and many other regulars.
However, whatever the netted out forcing effect of all other factors combined, it is ultimately that latitudinal shifting that holds the balance so as to bring global average tropospheric air temperatures back in line with sea surface temperatures thereby maintaining system stability for more than 4 billion years.
My work simply presents a skeleton constructed from the primary players of sun (from the top down), oceans (from the bottom up) and atmospheric pressure (which sets the energy cost per unit of evaporation). Many other intelligent contributors here can probably graft on some flesh and skin to move us towards a more complete climate description in the years ahead.
I have presented a basic climate overview which fits the laws of physics and observations better than any other so far (in my humble opinion) but it does need extending and refining.
It would be nice if someone influential would pick it up, run with it and test it to destruction if appropriate. If it can withstand such a process we would see a major advance in climatology. If it cannot then I am proud that I did my best without bias either way.Any component left standing could still be useful.
I think this would be an ideal moment. Climategate 2 has delivered yet another blow to the consensus and those of us without bias would dearly like to see some sort of progress in the science by way of an alternative to that discredited theory.
Dave Springer said:
“As it gets warmer and warmer and more and more of the surface is covered by liquid there’s more evaporation and more clouds both of which cool the surface by first transporting heat away from the surface in latent heat of vaporization and second by forming highly reflective clouds which block warming sunlight from reaching the surface.”
That is nearly right but there is a problem in that global cloudiness decreased during the warming spell and is now increasing during the cooling spell (or at least lack of warming spell).
Unexpectedly the faster water cycle that offsets a warming trend is accompanied by LESS global cloud cover.
My suggestion that the process is controlled by latitudinal climate zone shifting would solve that problem.
The faster water cycle results in a more zonal / poleward set of jets. Being more zonal the jets are shorter but more vigorous with more vertical movement within the cloud bands throwing energy upward faster. However global cloudiness is reduced because what goes up must come down and so the high pressure cells either side of the jets intensify and low cloud within them dissipates.
A slower water cycle results in more meridional / equatorward and less vigorous jets which wander about over a much larger area. Since there is less vigour in the jets and less upward energy transfer the high pressure cells are weakened and more low cloud cover develops over larger areas.
The outcome is that the system is kept stable either way because in a warming spell more solar energy gets into the oceans from less clouds but the faster water cycle offsets the effect.
In a cooling spell less solar energy gets into the oceans from more clouds but the slower water cycle slows down energy loss to space to try to maintain system stability as long as possible.
The detailed mechanisms are set out in the articles I linked to earlier.
Being so counterintuitive it all seems unlikely at first but if you think about it and compare to observations there seems to be no other way to square the circle.
This morning I just posted an article about this new paper.
Little by little the truth (as little as we know of it) will emerge for all to see.
Will it be to late for Europe? The US?
Poverity kills!
So, based on that study, we should be grateful that we are building in a 2 degree “cushion” in temperature. That way, if natural processes lower the temperature, we don’t enter an ice age (the extra CO2 saves us).
Earlier I had written … Don’t expect many comments. (in the MSM)
This paper argues strongly against the case for dire AGW. Here is the reason that is so …
From http://www.bbc.co.uk/news/science-environment-15858603
(25 November 2011 Last updated at 10:48 ET )
I interpret the above as implying …
1) Assertion: “We have a model which describes the behavior of climate. This model is predominantly calibrated to the most recent 150 years of historical measurements. This current 150 year interval of data, as applied to our model, suggests that rising CO2 levels will have dire consequences.”
Interpretation: The climate model uses the current 150 interval to indicate a future (as in future bounded, fixed, clamped, determined value) of dire consequence.
2) Assertion: ( unstated ) By using the ‘climate model’ with the present 150 year interval of historical measurements to predict a future of dire consequence, we also unavoidably make a prediction as to the palaeoclimate.
Interpretation: In using the ‘climate model’ with current data to predict future outcome, the past performance is unavoidably constrained.
3) Assertion: “New evidence gained from reconstruction of palaeoclimate conditions indicates that our ‘climate model’ prediction of immanent dire consequence is implausible (impossible). ‘The results are published in Science‘. This challenge to the status quo is credible.”
Interpretation: Houston, we’ve had a problem. We’ve had a main B bus undervolt.
4) Assertion: “The ‘climate model’ can be brought back into correspondence with past palaeoclimate performance and future dire expectation by reducing ‘the expected rise in average surface temperatures to just over 2C, from 3C.’ ”
Interpretation: For me personally, the corrective adjustment is akin to placing the ‘climate model’ between jaws of a vice and applying a Procrustean reduction to 2 parts in 3. The ‘climate model’ that is presently used is not very good. It is in serious trouble.
I admire the BBC’s candid reporting of this new study. It affirms their impartiality in the face of considerable awkwardness.
Further comments from the BBC article quoted below actually acknowledge the severity of this challenge to the current ‘climate model’. They are more about reticent acknowledgement than refutation.
From http://www.bbc.co.uk/news/science-environment-15858603
(25 November 2011 Last updated at 10:48 ET )
Stephen Wilde,
The main reason I ignored your latitudinal shifts argument was that climate zone latitudinal shifts was THE prediction of the Warmers from the begining (30+ years ago).
It simply didn’t happen to the degree predicted and what latitudinal shifting that did occur appears to be mostly ENSO related.
So the Warmers quietly ‘forgot’ about latitudinal shifts, or at least hoped others would forget.
But latitudinal shifts as a non-linear feedback makes sense. Whether it is the main component I don’t know, but its clear to me that the Earth’s climate must be dominated by fast (faster than GHGs) non-linear -ve feedbacks. Otherwise it would go unstable.
When I get more time, I will read your stuff in detail.
regards
Are the milankovitch cycles considered?
“It simply didn’t happen to the degree predicted and what latitudinal shifting that did occur appears to be mostly ENSO related.”
Correct and that ENSO influence forms part of my bottom up oceanic portion.
However there was substantial such shifting from MWP to LIA to date which was far greater than the ENSO influence alone could have provided.
Furthermore I noted the poleward shift going into reverse around 2000 and the process has consolidated since and of course that is against AGW theory.
Thus my attention turned to the likelihood of a top down solar effect.
Then the recent very quiet sun was linked to a record negative AO so the evidence is accumulating in favour of my hypothesis.
Latest addition to my articles just out here:
http://climaterealists.com/index.php?id=8723
“CO2 or Sun? Which One Really Controls Earth’s Surface Temperatures?”
richard
“Observational data during the instrument periiod suggests that the climate sensitivity to CO2 is small. This is, of course, one reason why model projections are running so warm when their projected results are viewed against current observational data.”
if you look at observation data in the past 150 years you are estimaing the TCR.
Transient
Climate
Response
This response, like the response of your car when you FIRST press the pedal down,
is not the steady state response. The TCR is less than the ECR.
So, do some reading, learn the difference between the TCR and the ECR
Think about this.
If I ask you what the response of your car system is ( velocity) to a full forcing of 300 Hp
You can have several answers. A transient response ( 0-60 in 3 seconds) or steady state
response 120mp top speed.
The climate response comes in two flavors: TCR and ECR. The 150 year record is not
long enough to measure the total response to doubling of C02. You can measure the TCR
and then use the TCR to estimate the ECR. Many studies do this. They look at volcano
responses.. relaxation response.
petermue says:
Sometimes computer modelers have a tendency to think that if their model doesn’t match reality then reality must be wrong.
With climate “scientists” this appears to be the norm.
With them only sometimes thinking that if their model dosn’t match reality then just maybe the problem is with the model.
steven mosher says:
November 25, 2011 at 11:52 pm
This response, like the response of your car when you FIRST press the pedal down,
is not the steady state response. The TCR is less than the ECR.
It is a feeble excuse for the failure to understand what is actually going on, and perpetuate an unsustainable hypothesis.
North Atlantic has a 50ish year time constant, with response boosted when it falls into phase with the solar activity:
http://www.vukcevic.talktalk.net/CET-NV.htm
Now even NASA’s Dr. Hathaway agrees that solar input matters, but doesn’t know how.
Listen to Dr. Hathaway’s most recent interview (22/11/11) on: Sunspots recalibration (Dr. Svalgaard’s pet subject), Livingstone&Penn effect, forthcoming Grand minima and global warming:
http://www.vukcevic.talktalk.net/NFC7a.htm
Henry@Stephen Fisher Mosher
Do you mean the GHG effect of CO2? Or that it acts as fertilizer & plantfood, thereby helping to increase the greening of the planet?
Carefully look at my tables
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
Note the difference in the results of the NH and the SH if you look at the mean (average) temps.
Does not make sense to say it must be the GHG effect because otherwise NH and SH should be the same?
An interesting aspect I find is that a correlation can be picked up if you compare the results in my tables with that of the leaf area index shown in the world chart here:
http://wattsupwiththat.com/2011/03/24/the-earths-biosphere-is-booming-data-suggests-that-co2-is-the-cause-part-2/
In the red areas, where we find earth is blooming, and more greening, you will note from the results in the tables that the increase in maxima is picked up and trapped by the increasing vegetation. In the blue areas, where substantial de-forestation has been going on, you will find mean temperatures and minima declining or staying unchanged, even though maxima are rising.
So, it seems if you want the earth to be greener, the natural consequence is that it will also get a bit warmer.
“CO2 or Sun? Which One Really Controls Earth’s Surface Temperatures?”
The surface warming is substantially a spurious Tmin signal, which I am looking at right now.
Lots of data to download and collate. It’s scandalous that climate scientist’s awash in grant money aren’t doing this.
Now just you watch… the warmists will soon produce a peer reviewed paper that will contradict this one.
I’m not being silly. It will happen. Heck, if the ‘climategate’ IPCC scientists could dictate that it is Co2 that influences temperature rather than the other way round, and if they could dictate that Co2 is the key driver of climate change, heck… they will have no problem exposing this latest paper as clearly being unreliable and probably indirectly funded by ‘big oil corporations’ thus making the paper nothing but propaganda. And of course, their message will be heavily publicised by the ‘impartial’ BBC and the UK’s ‘objective’ newspaper, the Guardian.
Such is the state of climate science. Any climate study is now held with deep suspicion by the public, and seen as simply trying to promote one or the other side of the climate debate. It’s all become ridiculous… like going around in a circle and getting nowhere!
steven mosher says:
November 25, 2011 at 11:52 pm
Transient
Climate
Response
———————–
The Transient Climate Response timeline depends on energy accumulating in ocean heat, ice-sheet melt and land (and where-ever else it can accumulate) and thus not influencing the surface temperatures yet.
But we can only find between 0.0 W/m2 and 0.3 W/m2 accumulating right now so the Transient Response is very close to the full Equilibrium Climate Response right now.
The science has been hiding behind TCR for several years now but it is only equivalent to a delay between 0 to 7 years at today’s rates.